Peripherin/rds (P/rds) interacts with other proteins to build and maintain the disc rim structure of rods and cones. Our goal is to determine the functional properties of P/rds and its interacting partners and to investigate the molecular and biochemical abnormalities associated with disease-causing mutations in this gene. Utilizing proteomics, we have identified several proteins which interact with the P/rds complex. In this application, we will test our main hypothesis that P/rds and rom-1 exist in a primary complex that associates with an auxiliary complex linking the disc rim to the plasma membrane (PM). We propose that the primary complex is composed of hetero- and homo-tetramers, octamers and/or oligomers. Through proteomic studies, potential members of the auxiliary protein complex were identified and we propose to study their role in P/rds complex formation and disc rim morphogenesis of both rods and cones. Aim 1 will test the hypothesis that P/rds complex is different in composition between inner (IS) and outer segment (OS) regions, as well as between rods and cones. Experiments in this aim should investigate the differences in primary complex formation in the IS to that in the OS and identify rod/cone-specific interacting partners. Aim 2 evaluates will investigate the association between P/rds complex and the cone cGMP gated channel. Conventional biochemical techniques of protein-protein interactions and colocalization at the ultrastructural level will confirm and map the sites of their association with P/rds and rom-1. Aim 3 will characterize transgenic mice that express the C150S mutation in either rods or in cones to determine the role of C150S mediated inter-molecular disulfide-linked homodimers on rod and cone disc morphogenesis and its effect on P/rds primary and auxiliary complex assembly. Aim 4 investigates modifications in P/rds-primary or -auxiliary complex formation associated with diseases-causing mutations in P/rds. Our previous results indicate that either self-associations of P/rds or association with rom-1 to form tetramers are critical for stability and OS localization of P/rds and rom-1. R172W and C214S transgenic retinas will be used to define the perturbations in complex assembly and disc structure caused by these mutations in P/rds. Studies put forth in this application will provide biochemical and physiological evidence to define the role of P/rds, and its associated proteins, during genesis of rod and cone OSs. Also, the influence of the disc rim region on phototransductory signal transmission to the PM.